How do can we teach our kids that mental hygiene is just as important as physical hygiene?

or children from a young age might say I don't want to brush my teeth I don't feel like brushing my teeth I'm going to sleep anyway what do I have to brush my teeth for so we try to promote and teach hygiene the best hygiene practices to live a physically healthy life physical exercise and so on so in the mental space as well there are mental hygiene practices that we can promote teach educate about how to practice mental hygiene what does that look like